Here is a thread mentioning the Heritage auction on November 5, 2015, with T206s from the Endicott, NY find. The auction included a near-set of Sovereign backs plus a Lenox back, a Plank, and a Magie error, but it's not clear if these were part of the Endicott find.
http://www.net54baseball.com/showthread.php?t=213608
Based on this press release from Heritage, it sounds like the Sovereigns, at least, were part of the Endicott find:
https://www.ha.com/heritage-auctions...releaseId=2841
The only card I have from that find is an Art Fletcher with a Cycle 350 back:
